Long-range interactions for H(1s)-He(n^1,3P), H(1s)-Li(n²P) and He(1¹S)-Li(n²P) systems

Abstract

The dispersion coefficients C 6 for the H(1s)-He(n 1,3 P), H(1s)-Li(n 2 P) and He(1 1 S)-Li(n 2 P) systems with n = 2, 3 are calculated using variational wavefunctions in Hylleraas coordinates.

Theoretical study of pressure broadening of lithium resonance lines by helium atoms

“…At large R, the potential energies vary as −C 6 /R 6 . The theoretical values of C 6 of 22.51 for the X 2 Σ state [21], 28.27 for the A 2 Π state [22] and 50.69 for the B 2 Σ state [22] were adopted. For each potential energy curve, the data in different segments were smoothly connected with a cubic spline procedure.…”

A Fragile Union Between Li and He Atoms

“…The long-range coefficients C 6 are taken from the calculations of Zhu et al [20], and C 1 and C 2 are determined by fitting to the potentials calculated by Behmenburg et al [19]. We first performed single-channel calculations of the energy levels of the A 2 Å and B 2 AE model potentials.…”

Highly improved upconversion luminescence in NaGd(WO4)2:Yb3+/Tm3+inverse opal photonic crystals

“…[8][9][10][11] Er 3+ or Tm 3+ offers some ideal intermediate states for two-step or multi-step UC population channels under the pump of 980 nm light, whereas Yb 3+ has a relatively strong absorption around 980 nm. 13 Actually, in UC phosphors, the existence of large phonons may also offer some novel population channels and may sometimes favor UCL. 12 It should be highlighted that some recent studies indicate that in some oxide compounds with relatively large phonon thresholds, Er 3+ /Yb 3+ or Tm 3+ /Yb 3+ co-activated phosphors also demonstrate intense UC emissions.…”